Boring tool



Sept. 14, 1937. J. P. FRANCESCO BORING TOOL Filed Afig. 10, 1936 2Sheets-Sheet 1 Ja//z P, 52 2766560.

Sept. 14, 1937. J. P. FRANCESCO 2,092,755

BORING TOOL Filed Aug. 10, 1936 2 Sheets-Sheet 2 6 4 r 9 a "Ma 7. w x mJ 6 4 fi m m 2 Q J y 9 a f P w fi m J J 0 5 2 4 F 6 4 P an 0 4 J z.l||!.................| /w E. a.

Patented Se t. 14, 1937 UNITED STATES PATENT OFFICE 4 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 757) This invention described herein may be manufactured and usedby or for the Government for governmental purposes, without the paymentto me of any royalty thereon.

This invention relates generally to boring tools,

but more particularly to an improved bit adapted for drilling holes ofvarious contours.

The principal object of the invention is to provide a simple and.-efiicient tool of the class described, which may be cheaplymanufactured,

and one which may be easily varied in its operation to drill holes ofvarious contours and dimensions.

Another object of the invention is to provide means by which an ordinarybit may be converted into a tool of the class described.

Other objects of the invention consist of certain novel details ofconstruction and arrangement of parts as hereinafter shown in thedrawings, described in the specification, and more particularly definedin the accompanying claims.

Briefly stated the invention-comprises a bit or drill provided with acup-shaped sleeve and a cam mechanism for operating a radially movable 5cutter slidably attached to said-drill. When the operator holds thesleeve stationary and revolves the drill the blade of the cutterdescribes a contour which outlines the side walls of the hole drilled,the contour depending on the size and 30 shape of the cam used.

Referring to the accompanying drawings in which corresponding parts areindicated by similar reference characters:

Fig. 1 is a front elevation of a partially sec- 35 tionalized assembly,showing a standard form of brace and the preferred form of improved bit,provided with a gear operated cam;

Fig. 2 is a partially sectionalized side elevation of the assembled bitshown in Fig. 1;

40 Fig. 3 is a top plan view of the cutter shown in Figs. 1, 2 and 4;

Fig. 4 is a side elevation of the improved bit shown in Fig. 2, providedwith a grooved cam;

55 in Fig. 6;

Fig. 5 is a partially sectionalized front elevation of a modified formof bit in which the'oper- Fig. 9 is a bottom plan view of the sleeveshown in Fig. 6;

Fig. 10 is a partially sectionalized detail view taken on the line '|--1of Fig. 6, showing a portion of the cam groove and spring mechanism; 5and Fig. 11 is a front elevation of a handle and bracket shown in Fig.6.

Referring to the drawings, particularly Figs.

1, 2 and 3, the numeral (l) indicates the im- 10 proved bit and (2) astandard form of brace or bit stock. The brace comprises a crank (3)provided with handles (4) and (5) and a chuck comprising externallytapered and threaded resilient gripping members (6), and an internally15 tapered and threadedsleeve (1) adapted to operate said grippingmembers and thus form a detachable connection for the shank of said bit.

The bit which is indicated by the numeral (l) comprises an ordinary bitor drilling shaft (8) 20 having a squared and tapered shank (9) adaptedto fit the chuck of the brace (2), the opposite end of the bit, which isgenerally of enlarged diameter as shown in Figs. land 6, being providedwith the ordinary drilling point (I0) and rotary cutter (H) to which therotary movement of the brace (2) is transmitted and which I are designedto drill a circular hole. To the construction as set forth,which'comprises the ordinary circular drill, the following elements areadded which convert this drill into an instrument capable of drillingholes of any desired size and contour, depending on the size and shapeof cam used, as will be described.

To the shaft is rotatably fitted a. cup-shaped sleeve (l2) retainedthereon by the washer (l3) and screw (l4). To the bottom portion of thissleeve (I 2), which bottom portion is of smaller diameter, is fitted abevel gear (l5), rigidly attached thereto by the screw (IS). The bevelgear (I 5) meshes with another bevel gear (I1) rotatably mounted on ashaft or bearing memher (I 8) which fits within a hole, preferably ofsquare contour, passing through the shaft (8) of the bit at right anglesthereto. This bearing member (i8) is squared at one end thereof toprevent rotation within the shaft (8) of the bit, and is rounded for theremainder of its extent and provided with threads adjacent its otherextremity. The rounded portion of the shaft is provided for thereception and free rotation of the gear (l1) and a cam (l9) which areretained on the bearing member (l8) by a nut (20). In order to assurerotation of the cam (IS) with the gear (I'I) pins (2|) are provided.These pins to the axis of the bit shaft. If the cam is of (2|) projectfrom the face of the gear into openings in the cam (I9) as illustratedin Fig. 2. A longitudinally extending plunger (22) is slidably mountedwithin brackets (23) and (24),

said brackets being attached to the shaft, either by members whichproject through holes provided therein, and which are riveted to theshaft as shown in Figs. 2 and 4, or by any other suitable manner.

The upper end of the plunger (22) is rounded to accommodate it forsliding contact with the cam (l9) and the lower end of the plunger (22)is curved at right angles, and this extremity slidably fitted within aslot (25) in a bell crank lever (26). The lever (26) is pivotallymounted to the enlarged lower portion of the shaft (3) of the bit bymeans of a pin (21). The opposite arm of the lever (26) is provided withanother slotted opening (28) in which is slidably mounted a pin (29)projecting from a radially movable cutter (30). It will be noted thatthe cutter is provided with several holes for the reception of the pin(23), so that various sizes of holes may be drilled. The radiallymovable cutter (30) is beveled on its-upper and lower surfaces andslidably fitted within beveled grooves out within the enlarged portionof the shaft (8) of the bit (I), preferably at right angles to thelongitudinal axis thereof, or at a slight incline to this right angularposition, dipping in the direction of the cutting blade (3|) which islocated at one extremity of the cutter. The cutter is also beveled fromthe face on the leading or cutting'end toward the rear, as shown in Fig.3.

It will be seen from the description of the construction that when thebrace (2) is rotated, and the cup-shaped sleeve (|2) held stationary, soas to prevent rotation thereof, that the bevel gear (H) is rotated as itis rolled around the bevel gear (l5), by the rotation of the shaft (8)on which the gear (i1) is mounted. The gear (II) will revolve the cam(IS) in unison therewith, and by the interaction of the cam and plunger(22) and the intermediate bell crank lever (26) the rotary movement ofthe cam is translated into a reciprocating movement in the cutter (30).The movement of the cutter (30) corresponds to the movement of the cam(l9) and cutting blade (3|) thus describes a contour similar to that ofthe edge of the cam, in a plane at right angles square outline as shownin Fig. 1, the cutting blade will describe a square in its movement, orif it is desirable to produce a hole hexagonal in shape, or of any othercontour, a cam of the particular-shape will cause the cutting blade tomove along the desired contour.

The same result may be obtained by forming a cam (32) on the bottomsurface of the cupshaped sleeve (33) so as to produce any desiredmovement of the cutting blade as shown in the construction illustratedin Fig.. 5. In the modified form shown by this illustration it will beseen that when the sleeve is held stationary, a reciprocating movementof the plunger (22) is produced as the bit shaft (8) is rotated, andthis reciprocating movement may be transmitted to a lever (28) andcutter (30) (not illustrated in this view) in the same manner as shownin Figs. 1 and 2.

The sleeve (33) is retained on the shaft (8) by means of a collar (34)which is fastened to the shaft by the pin (35). The collar is providedwith a rim (36), which is rotatably mounted between the floor (31) ofthe cup-shaped opening in the sleeve, and an annular ring (36) which isretained within the opening by the screws (39). The use of this type ofcam eliminates the neces-. sity of operating the plunger (22) by meansof bevel gears, and thus simplifies the construction.

In Figs. 1, 2 and 5, it will be noted that the top ofthe plunger (22) iskept in constant contact with the cams (l9) and (32) by means of thetension spring (40) which is attached at one end to the plunger, and atthe other to the upper bracket (23). Fig.- 4 shows the improved bit inwhich a modified form of cam is used, permitting the omission of thespring (40), as the cam is provided with a groove (4|) into which theupper end of the plunger (62), which is bent at 90 to the longitudinalaxis, is slidably fitted. With this construction the plunger is elevatedand lowered as its upper end follows the cam groove (4|). The lower endof the plunger is pivotally connected to the bell crank lever (26) whichoperates the transversely movable cutter as shown in Figs. 1 and 2. Theonly difference between the two forms of bits, that shown in Fig. 4 andthe one shown in Figs. 1 and 2, being the construction of the cam, andthe elimination of the spring (40), and 90 bend at the upper end of theplunger, where it fits into the cam groove (4|).

Another modified form of bit is shown in Fig. 6. In this construction asleeve (42) is provided, which extends over the greater portion of thelength of the bit shaft (8). The lower portion of this sleeve is ofincreased diameter to fit the increased diameter of the shaft, and alsoto permit the formation of a cam groove in its lower surface. The sleeveis provided with radially projecting handles (43) which when held by theoperator prevents the rotation of the sleeve with the rotation of theshaft (8).

In this type of construction the shaft (8) is provided with a groove(44) which extends around its circumference and the sleeve (42) isprovided with retaining screws (45), the ends of which project withinthe groove to prevent longitudinal movement of the shaft with respect tothe sleeve. The handles (43) are detachably mounted to the upper portionof the sleeve (42) by means of brackets (46) integrally formed with saidhandles and provided with bayonet openings (41) which fit over pins (48)radially projecting from the outer surface of the sleeve. The lowerportion of the bit shaft (8) as mentioned above, is of increaseddiameter as indicated by the numeral (49) and the internal diameter ofthe sleeve is also of increased diameter, as indicated by numeral (50),to fit over this lower portion of the shaft. The interior surface of theportion of the sleeve having an increased diameter is provided with agroove (5|) into which is fitted a bushing (52). This bushing is adaptedto provide a more accurate fit for the shaft within the sleeve, and thusprevent eccentric rotation of the former. The transversely reciprocatingcutter (53) is beveled on its upper and lower surfaces, as indicated bythe numerals (54) and (55), to fit a correspondingly cut groove in theenlarged portion of the shaft (8) in the same manner as shown in Figs.1, 2 and 4, but in this instance, the groove is cut at a slight angle toa plane, normal to the longitudinal axis of said shaft to allow a slightdip of the tool toward its cutting end. This is done to provide ampleclearance for the cutting point of said tool. The cutting tool issomewhat similar to that shown in Figs. 1, 2, 3 and 4, except that it isprovided with a more extended bevel from given its reciprocating motiondirectly from the cam without necessitating any intermediate plunger andlever mechanism as shown in the types illustrated by Figs. 1, 2 and 4.This is accomplished by providing the bottom of the sleeve (8) with acam groove (64) into which is fitted a roller (55), rotatably mounted onthe upper surface of the cutting tool. The upper surface of the cuttingtool is drilled with several holes (56) for the reception of a pin (51)on which the roller (55) is mounted; upon revolution of the shaft theroller follows the path of the groove in the lower surface of the sleeveand thus imparts to the edge (58) of the cutter (53) a movementcorresponding to the contour of the groove. In order to facilitate themovement of the roller within the cam groove, the sleeve in the plane ofthe groove is provided with tapped openings for the admission of helicalsprings (59) and retaining screws (60). The springs (59) react againstthe free ends of metal strips- (6|) which are hingeably mounted on theouter walls of the cam groove (54) and which extend partially into thepath of said roller. The springs being located at the corners of saidgroove are compressed by the roller passing over the strips and when theroller has reached the end of an arcuate path the spring in regainingits normal extent, imparts an impulse to the roller which starts it inits new direction in the cam groove.

Thus the action ofv the springs is to prevent square holes.

' described above.

sticking or binding of the rollers in the corners of the cam groove asit follows the contour thereof.

The cam groove shown in Fig. 9 is for cutting This particular shape ofgroove is required to allow for the movement of the cutter which is in aslightly inclined path as It also provides for sufficient clearance forthe beveled blade as the cutting edge describes the desired path.

Having described my invention, what I claim as new and wish to secure byLetters Patent is:

1. A bit of the type described, comprising a central shaft having achuck shank and a drilling point, a normally non-rotatable sleeve inwhich said shaft is rotatably mounted, a bearing member mounted on saidshaft having its axis normal thereto, a cam rotatably mounted on saidbearing member, means in connection .with said sleeve and said cam,comprising bevel gears, adapted to rotate said cam upon rotation of saidshaft, a transversely movable cutter, slidably mounted on said shaft,and means in connection with said cam and said cutter, comprising aplunger and lever, adapted to produce reciprocating movement of saidcutter upon rotation of said cam.

2. A bit of the type described, comprising a central drilling shaft, anormally non-rotatable sleeve in which said shaft is rotatably mounted,a bearing member projecting normally from said shaft, a cam rotatablymounted on said bearing member, means in connection with said sleeve andsaid cam adapted to produce rotation of said cam with the rotation ofsaid shaft, a transversely movable cutter slidably mounted on saidshaft, and means in connection with said cam and said cutter adapted toproduce reciprocating movement of said cutter upon rotation of said cam.

3. A bit of the type described, comprising a central drilling shaft, anormally non-rotatable sleeve in which said shaft is rotatably mounted,a bearing member projecting normally from said shaft, a cam rotatablymounted on said bearing member, means comprising bevel gears inconnection with said sleeve and said cam adapted to produce rotation ofsaid cam with the rotation of said shaft, a transversely movable cutterslidably mounted on said shaft, and means comprising a pivotallyconnected plunger and lever, in connection with saidcam and said cutteradapted to produce reciprocating movement of said cutter upon rotationof said cam.

4. A bit of the type described, comprising a central drilling shaft, anormally non-rotatable sleeve in which said shaft is rotatably mounted,a bearing member projecting normally from said shaft, a cam rotatablymounted on said bearing member, means comprising bevel gears inconadapted to vary the extent of transverse movement of said cutter.

JOHN P. FRANCESCO.

